1. Field of the Invention
The present disclosure relates to a touch stylus and a related optical-mechanical system, and more particularly, to a touch stylus capable of detecting pressure on its tip and a related optical-mechanical system.
2. Description of the Prior Art
Currently, in the market of various kinds of consumer electronic products, touch panels have been widely applied in portable electronic devices, such as personal digital assistants (PDA), mobile phones, and notebooks for serving as the interface of information communication tool between the users and the electronic devices. Since modern electronic products increasingly become smaller, thinner, and lighter, the display with a touch panel has gradually become the key component of various electronic products in order to save space and to replace conventional input apparatuses, such as keyboard and mouse, leaning on the trend of requirement of human-based designed flat computer.
For example, the portable electronic device has advantages of thin volume and large dimension screen for displaying the information, so the touch panel is usually utilized to be human-machine interface between the users and the portable electronic device. The touch panel can display patterns and characters, and further can be a touch input module. When the user presses the touch panel, the touch panel can detect a position of pressure, and output a control command according to the pressure position on a surface of the touch panel, so as to control the application program installed in the portable electronic device.
A conventional touch stylus includes a capacitive touch stylus and an electromagnetic touch stylus. The electromagnetic touch stylus includes an antenna to receive an electromagnetic signal, has drawbacks of inconvenient operation and expensive manufacturing cost. An electromagnetic coil is disposed inside a body of the electromagnetic touch stylus. When a tip of the touch stylus is pressed, the tip moves relative to the body, and a movement of the tip drives the electromagnetic coil to generate magnetic flux variation, so the electromagnetic touch stylus calculates the pressure on the tip according to the magnetic flux variation. Besides, the electromagnetic touch stylus can further obtain the pressure on the tip according to variation of capacitance value by compression. The capacitive touch stylus does not include an additional receiver, and is utilized to paint a writing track without recording the pressure variation. The tip of the capacitive touch stylus is huge, such as 5-6 mm, for accommodating capacitors and related components. The capacitive touch stylus is inconveniently to be held.
The conventional touch stylus further includes an optical touch stylus. The conventional optical touch stylus can not record pressure variation of the tip. The latest type optical touch stylus detects luminous flux to show the pressure variation of the tip, and has a drawback that detection is interfered easily by ambient light. An integration of the electromagnetic touch stylus, the capacitive touch stylus and the optical touch stylus can design a touch stylus has pressure detection function. Mechanical design and circuit design of the integration touch stylus is complicated that results in expensive manufacturing cost. Therefore, design of a low cost touch stylus without specific receiver for detecting pressure on the tip is an important issue in the computer industry.